Support xyzservices for tile management

[martinfleis]

Is your feature request related to a problem? Please describe.

With the @geopandas team, we have built a new package called xyzservices to serve as a unified place for XYZ tile management. The idea behind this is that other packages will depend on that instead of having their own system and list of supported tiles hard-coded.

I have opened an issue about the support of xyzservices in holoviews -> holoviz/holoviews#5057 but it seems that the base map tile support in geoviews is using another implementation? If that is true, I'd suggest implementing the same support I have outlined in the holoviews issue.

I'll leave the details out (see the linked issue for more), so just quickly for the sake of completeness:

Describe the solution you'd like

1. support xyzservices.TileProvider as an input of gv.WMTS and/or gv.Tiles (not sure about the difference, sorry).
2. refactor tile management to map providers to the xyzservices objects and remove hard-coded metadata.

Additional context

holoviz/holoviews#5057